I think this may have been asked before but not sure anyone has done it, so may not know...
Not sure if the seats physically fit? Two things to check there (I think)...
The rails - distance between centres of the bolts along the rail, and the width.
Seat width, not sure if the E46 is any wider, in the cabin, but worth checking the room from the inner runner to the centre console.
With regard to the wires, have a look on RealOEM at each car and see if the connectors are the same, if so you may be in luck. Then get a look at the E46 switch panel (or owner's manual) and make sure the operation is the same - the E46 is an older car and may use a slightly different system there. Then, all being well, have a look at the WDS (there's a link through from my signature) and check that the signals are the same for the seat functions - power and heating... or that they are using the same technology.
Actually, see about reverse engineer the solution... check the E46 forums and see if anyone has fitted the seats... you could try searching from something around the steering wheel and M3, we had someone from an E46 M3 forum on here asking for steering wheel measurements. Try PMing them for the measurements above, they may return the favour.
ADD: I'm quite nerdy so if no one comes forward with any better info am happy to help with the WDS stuff.
